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Sunday, November 23, 2008

Gelatinization Properties of Heat-Moisture-Treated Katakuri Starch and Its Elasticity at Near the Sol-Gel Transition (Abstract)

Aikawa Rieko, Akuzawa Sayuri, Sawayama Shigeru, Kawabata Akiko

The gelatinization characteristics of the native and heat-moisture treated(HMT) starches from katakuri, potato, and edible canna and their elasticity at near the sol-gel transition point were investigated. The swelling power and solubility of each HMT starch were greatly suppressed in comparison-with those of each native starch. The X-ray diffractograms showed that the heat-moisture treatment converted the B type pattern to the A type in potato and edible canna starches, whereas katakuri starch did not and indicated the A type with only 2 diffraction peaks, at 4a and 6a. The viscograms of HMT starches indicated greatly suppressed viscosity without breakdown. The digestibility of the HMT starch with .ALPHA.-amylase was found to be more susceptive than that of the native starch. The concentration dependence of the mechanical properties of native and HMT starches at near the sol-gel transition point was analyzed based on the scaling law derived from the percolation theory. The gelation concentration of the HMT katakuri starch was higher than that of the native starch. The critical concentration of the native and HMT katakuri starches for gelation were estimated to be 1.5wt% and 2.5wt%, respectively. The HMT katakuri starch formed softer gels below the critical concentration than the native starch did, and it formed firmer gels above it. It was recognized that the scaling law could be applied to the native and HMT katakuri starches and determined that the critical exponents were 3.2 and 3.7, respectively; but it could not be applied to the native and HMT potato starches or to the HMT edible canna starch. (author abst.)